From a wave: Arm turn half, new centers arm turn 3/4 and spread. The new ends side step together and Trade, then spread as those who did the 3/4 arm turn now side step together, arm turn 3/4 again and re-form the wave.
Vince Spillane 1974
This definition is from The Handbook of Modern Square Dancing by Jay King.
It is provided here for informational and educational purposes only.